Accelerating of cheese aging to improve cost efficiency through a reduction of storage space is becoming more important to the cheese industry. Currently, lipases from two different sources, animal pregastric glands, and animal pancreases, are being added to cheese curd as accelerators. A third source, microbial lipases, has been used in commercial production of strongly flavored cheeses, but not mild cheeses.
Lipases derived from the pregastric gland of kid, calf and lamb are currently being added to accelerate ripening in cheese of Italian type (Provolone, Romano, Parmesan) where the characteristic rancid flavor of low molecular weight free fatty acids (e.g. butyric acid) is desirable. However, when these pregastric lipases are used to accelerate mild flavored cheese, e.g. Cheddar, too much of the low molecular weight fatty acids are produced and a rancid flavor develops. When the animal pancreas lipases are used in a high concentration, excessive amounts of lauric acid is produced in the cheese, making a soapy taste. Moreover, unless highly purified, these lipases can contain an abundance of protease which although in small amounts aids cheese softening, in larger amounts it produces bitter off-flavors.
In the search for lipases showing desirable ripening characteristics, numerous organisms such as Pseudomonas fragii, P. fluorescens, Staphylococcus aureus, Clostridium lipolytica, Geotrichium candidum, Penicillium roqueforti, Aspergillus niger, A. flavus, A. oryzae, Candida cylindracea and Rhizopus oligosporous, have been used in laboratory studies. Many of these microbial lipases are not yet available commercially. In a study of various lipases for cheese ripening, Harper, W. J., [J. Dairy Science 40 556 (1957)], the following data has been developed with respect to selective liberation of free fatty acids from 20% butterfat cream.
TABLE 1 ______________________________________ Release of Free Fatty Acid from 20% Butterfat Cream Mol. % Produced in 3 hrs. @35 C. Ca- Ca- pro- pryl- Lipase Source Butyric ic ic Capric Lauric ______________________________________ Imported kid rennet 32.8 11.3 7.1 11.8 33.6 (paste) Pregastric esterases kid 44.4 15.2 7.6 12.3 21.5 lamb 48.1 8.6 14.2 9.3 19.3 calf 36.7 8.9 14.8 10.7 39.0 Domestic calf rennet 10.7 3.1 trace trace 86.5 Milk lipase 13.5 8.2 10.2 8.7 60.0 Pancreatic lipase 8.4 2.1 trace trace 89.1 A. niger lipase 43.1 18.9 20.2 17.5 trace ______________________________________
Little information is available on the relationship between specific free fatty acids and flavor intensity in cheese although the presence of butyric acid usually is associated with strong rancidity development in strong cheese and the presence of large amounts of lauric may lead to a soapy flavor. Longer chain fatty acids have been linked to fruity flavors. It is generally noted that all of the even numbered free fatty acids are present but the concentration of the specific fatty acids varies in different types of cheese.